Abstract:

The present invention relates to a polyvinyl acetal resin having a
specific repeating structural unit, an electrophotographic photosensitive
member using the polyvinyl acetal resin, and a process cartridge and an
electrophotographic apparatus each having the electrophotographic
photosensitive member.

Claims:

1-3. (canceled)

4. An electrophotographic photosensitive member, comprising:a support;
anda photosensitive layer provided on the support, wherein the
photosensitive layer comprises a laminated photosensitive layer having a
charge generation layer comprising a charge generation substance and a
charge transport layer comprising a charge transport substance, and a
charge generation layer comprises a polyvinyl acetal resinwherein the
polyvinyl acetal resin comprises a repeating structural unit represented
by the following general formula (1): ##STR00042## where X11
represents a substituted or unsubstituted ethylene group, a substituted
or unsubstituted propylene group, or a substituted or unsubstituted
butylene group, R11, R12, R13, and R14 each
independently represent a hydrogen atom, an alkyl group, or a methoxy
group, and Ar11 and Ar12 each independently represent a phenyl
group having one or more electron-donating substituents.

5. (canceled)

6. An electrophotographic photosensitive member according to claim 4,
wherein the photosensitive layer comprises an gallium phthalocyanine
crystal having a strong peak at a Bragg angle in CuKα
characteristic X-ray diffraction of 7.4.degree..+-.0.3.degree. and
28.2.degree..+-.0.3.degree..

7. An electrophotographic photosensitive member according to claim 4,
wherein the photosensitive layer comprises an oxytitanium phthalocyanine
crystal having a strong peak at a Bragg angle in CuKα
characteristic X-ray diffraction of 27.2.degree..+-.0.3.degree..

8. An electrophotographic photosensitive member according to claim 4,
wherein the photosensitive layer comprises an azo compound represented by
the following general formula (2): ##STR00043## where Ar21 and
Ar22 each independently represent a substituted or unsubstituted
aryl group, X21 represents a vinylene group or a p-phenylene group,
and n represents 0 or 1.

9. A process cartridge which: integrally supports the electrophotographic
photosensitive member according to any one of claims 4 and 6-8 and at
least one means selected from the group consisting of a charging means, a
developing means, a transfer means, and a cleaning means; and is
detachably mountable in an electrophotographic apparatus main body.

10. An electrophotographic apparatus comprising:the electrophotographic
photosensitive member according to any one of claims 4 and 6-8;a charging
means;an exposing means;a developing means; anda transfer means.

11. An electrophotographic photosensitive member according to claim 4
wherein in the general formula (1), X11 is an unsubstituted ethylene
group and R11, R12, R13 and R14 are each a hydrogen
atom.

12. An electrophotographic photosensitive member according to claim 4 or
11, wherein the one or more electron-donating substituents are each an
alkyl group.

Description:

TECHNICAL FIELD

[0001]The present invention relates to a polyvinyl acetal resin, an
electrophotographic photosensitive member containing a polyvinyl acetal
resin, and a process cartridge and an electrophotographic apparatus each
having the electrophotographic photosensitive member.

BACKGROUND ART

[0002]Electrophotographic photosensitive members each using an organic
material (organic electrophotographic photosensitive members) have
started to be mounted on a large number of electrophotographic
apparatuses (such as a copying machine and a printer) in recent years.
The research and development of a material to be used in an
electrophotographic photosensitive member have been vigorously conducted.

[0003]The research and development of a charge generation substance
typified by a phthalocyanine pigment or an azo pigment have been
particularly vigorously conducted. Various proposals concerning a novel
compound and the novel crystal form of a pigment have been made with a
view to improving sensitivity and durability.

[0004]In contrast, at present, research and development concerning a
binder resin for a photosensitive layer, in particular, a binder resin
for a charge generation layer of a laminated photosensitive layer have
not been conducted very vigorously.

[0005]Under such present circumstances, for example, JP-A-62-030254 and
JP-A-05-045899 each disclose a polyvinyl benzal derivative as a resin
having an improving effect on sensitivity and a reducing effect on a
residual potential. In addition, JP-A-62-035537 discloses a polyvinyl
acetal derivative.

[0006]In actuality, however, a commercially available product such as
polyvinyl butyral is used in most cases in consideration of coating
property and the property with which a charge generation substance is
dispersed. Accordingly, the properties of the charge generation substance
are not always exerted sufficiently.

DISCLOSURE OF INVENTION

[0007]An object of the present invention is to: cause a charge generation
substance to exert its properties (electrophotographic properties)
sufficiently; and provide a resin excellent in coating property and
property with which the charge generation substance is dispersed, the
properties being said to be contradictory to the electrophotographic
properties. Another object of the present invention is to provide an
electrophotographic photosensitive member using such resin, and a process
cartridge and an electrophotographic apparatus each having the
electrophotographic photosensitive member.

[0008]According to the present invention, there is provided a polyvinyl
acetal resin including a repeating structural unit represented by the
following general formula (1):

##STR00001##

where X11 represents a substituted or unsubstituted ethylene group, a
substituted or unsubstituted propylene group, or a substituted or
unsubstituted butylene group, R11, R12, R13, and R14
each independently represent a hydrogen atom, an alkyl group, or a
methoxy group, and Ar11 and Ar12 each independently represent a
phenyl group having one or more electron-donating substituents.

[0009]According to the present invention, there is provided an
electrophotographic photosensitive member, including: a support; and a
photosensitive layer provided on the support, in which the photosensitive
layer contains the polyvinyl acetal resin.

[0010]Further, according to the present invention, there is provided a
process cartridge which: integrally supports the electrophotographic
photosensitive member and at least one means selected front the group
consisting of a charging means, a developing means, a transfer means, and
a cleaning means; and is detachably countable in an electrophotographic
apparatus main body.

[0011]Further, according to the present invention, there is provided an
electrophotographic apparatus including: the electrophotographic
photosensitive member; a charging means; an exposing means; a developing
means; and a transfer means.

[0012]A coating liquid for a photosensitive layer (coating liquid for a
charge generation layer) using the polyvinyl acetal resin of the present
invention has good property with which a charge generation substance is
dispersed, and is excellent in coating property. In addition, an
electrophotographic photosensitive member using the polyvinyl acetal
resin is an electrophotographic photosensitive member which: causes a
charge generation substance to exert its properties sufficiently; has
high sensitivity; and shows high potential stability upon repeated use of
the member. In addition, the electrophotographic photosensitive member
can exert stable properties irrespective of a change in environment where
the member is used and changes in specifications of a process cartridge
or electrophotographic apparatus on which the member is mounted.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a view showing an example of the schematic constitution of
an electrophotographic apparatus having an electrophotographic
photosensitive member of the present invention.

[0014]FIG. 2 is a view snowing an example of the schematic constitution of
an electrophotographic apparatus provided with a process cartridge having
the electrophotographic photosensitive member of the present invention.

[0015]FIG. 3 is a view showing an example of the schematic constitution of
the electrophotographic apparatus provided with the process cartridge
having the electrophotographic photosensitive member of the present
invention.

[0016]FIG. 4 is a view showing an example of the schematic constitution of
the electrophotographic apparatus provided with the process cartridge
having the electrophotographic photosensitive member of the present
invention.

[0017]FIG. 5 is a view concerning the evaluation of an electrophotographic
photosensitive member for sensitivity and residual potential.

BEST MODE FOR CARRYING OUT THE INVENTION

[0018]Of the polyvinyl acetal resins, a butyral resin synthesized from
butylaldehyde and polyvinyl alcohol is well known. An electron-donating,
substituted triarylamine skeleton is introduced instead of an alkyl group
into a polyvinyl acetal resin of the present invention.

[0019]The use of such resin as a binder resin for a photosensitive layer
(charge generation layer) can improve the property with which a charge
generation substance is dispersed. The inventors of the present invention
consider that the use can improve, furthermore, the polarization of a
carrier excited by the charge generation substance, the property with
which charge is transported into the layer, and the property with which a
carrier is injected into a charge transport layer and/or a base layer
(layer between a support and the photosensitive layer). The inventors of
the present invention assume that, as a result of the improvement, the
sensitivity of an electrophotographic photosensitive member is improved,
the residence of a carrier is suppressed, a photomemory is reduced, and
potential stability and environmental property upon repeated use are
improved.

[0020]The polyvinyl acetal resin of the present invention can be
synthesized in the same manner as in an ordinary butyral resin. That is,
the resin can be synthesized by causing polyvinyl alcohol and an aldehyde
having an electron-donating, substituted triarylamine skeleton to react
with each other in, for example, a mixed solvent of ethanol and toluene
in the presence of an acid such as hydrochloric acid or sulfuric acid at
20 to 70° C.

[0021]The polyvinyl acetal resin of the present invention has a weight
average molecular weight in the range of preferably 10,000 to 500,000, or
more preferably 30,000 to 100,000. When the molecular weight is
excessively small, the dispersion stability of a charge generation
substance, or film formability is insufficient in some cases. When the
molecular weight is excessively large, a problem is apt to occur in
handling upon synthesis, and the viscosity of the resin upon dispersion
of a charge generation substance increases, with the result that the
insufficient dispersion of the substance occurs in some cases.

[0022]In addition, the polyvinyl acetal resin of the present invention has
a degree of acetalization of preferably 30 mol % or more, or more
preferably 50 to 85 mol %. When the degree of acetalization is
excessively low, the solubility of the resin in a solvent may reduce
excessively. In addition, the number of electron-donating, substituted
triarylamine skeletons reduces, so an effect of the present invention
cannot be sufficiently obtained in some cases. On the other hand, it is
difficult to synthesize a resin having a degree of acetalization in
excess of 85 mol %.

[0023]In addition, in the present invention, the content of a remaining
vinyl acetate component derived from polyvinyl alcohol as a raw material
is preferably as low as possible. Polyvinyl alcohol having a degree of
saponification of 85% or more is preferably used as a raw material. A
degree of saponification of less than 85% is apt to reduce a degree of
acetalization.

[0024]Examples of an electron-donating substituent include: alkyl groups
such as a methyl group, an ethyl group, and a propyl group; alkoxy groups
such as a methoxy group and an ethoxy group; a phenyl group; a phenoxy
group; and a benzyl group.

[0025]When the polyvinyl acetal resin of the present invention is used in
a photosensitive layer (charge generation layer) of an
electrophotographic photosensitive member, the polyvinyl acetal resin of
the present invention may be mixed with any other resin before use. The
resins are mixed in such a manner that a ratio of the polyvinyl acetal
resin of the present invention to the total mass of the resins is
preferably 50 mass % or more, or more preferably 70 mass % or more.

[0026]Hereinafter, specific examples (Exemplified Resin (1) to (13)) of
the polyvinyl acetal resin of the present invention are shown. The
following X11, R11, R12, R13, R14, Ar11,
and Ar12 correspond to X11, R11, R12, R13,
R14, Ar11, and Ar12 in the general formula (1),
respectively.

[0027]In the above general formula (1), X11 preferably represents an
ethylene group (unsubstituted ethylene group). In addition, all of
R11, R12, R13, and R14 each preferably represent a
hydrogen atom. In addition, the above electron-donating substituents
possessed by Ar11 and Ar12 are each preferably any one of the
alkyl groups; of the alkyl groups, a methyl group or an ethyl group is
more preferable.

[0028]A photosensitive layer of an electrophotographic photosensitive
member of the present invention may be a single-layer photosensitive
layer obtained by incorporating a charge generation substance and a
charge transport substance into a single layer, or may be a laminated
photosensitive layer having a charge generation layer containing a charge
generation substance and a charge transport layer containing a charge
transport substance. From the viewpoints of electrophotographic
properties, the photosensitive layer is preferably a laminated
photosensitive layer. In addition, of the laminated photosensitive
layers, an ordered photosensitive layer obtained by laminating a charge
generation layer and a charge transport layer in the stated order from
the side of a support is more preferable.

[0029]When the photosensitive layer is a laminated photosensitive layer, a
charge generation layer can be formed by: applying a coating liquid for a
charge generation layer prepared by dissolving the polyvinyl acetal resin
of the present invention in a solvent and by adding and dispersing a
charge generation substance to and in the solution; and drying the
applied liquid. The charge generation substance can be dispersed by using
any one of the dispersion machines such as: media type dispersion
machines including a sand mill and a ball mill; and liquid collision type
dispersion machines.

[0030]Examples of the charge generation substance include: azo pigments
such as monoazo, bisazo and trisazo; phthalocyanine pigments such as
metal phthalocyanine and non-metal phthalocyanine; indigo pigments such
as indigo and thioindigo; perylene pigments such as perylenic acid
anhydride and perylenic acid imide; polycyclic quinone-based pigments
such as anthraquinone and pyrenequinone; a squarylium dye; a pyrylium
salt; a thiopyrylium salt; and a triphenylmethane dye. Those charge
generation substances may each be used alone, or two or more kinds of
them may be used in combination.

[0031]Of the above charge generation substances, a gallium phthalocyanine
crystal having strong peaks at Bragg angles in CuKα characteristic
X-ray diffraction of 7.4°±0.3° and
28.2°±0.3° is preferable because a combination of the
crystal and the polyvinyl acetal resin of the present invention provides
excellent dispersion stability and excellent coating property. In
addition, the combination of the gallium phthalocyanine crystal and the
polyvinylacetal resin of the present invention exerts an improving effect
on sensitivity and a suppressing effect on an increase in light potential
upon repeated use at low humidity.

[0032]In addition, of the above charge generation substances, an
oxytitanium phthalocyanine crystal having a strong peak at a Bragg angle
in CuKα characteristic X-ray diffraction of
27.2°±0.3° is also preferable because a combination of
the crystal and the polyvinyl acetal resin of the present invention
provides excellent dispersion stability and excellent coating property.
In addition, the combination of the oxytitanium phthalocyanine crystal
and the polyvinyl acetal resin of the present invention exerts an
improving effect on sensitivity and a reducing effect on a residual
potential as initial effects, and a suppressing effect on a reduction in
light potential (falling phenomenon) upon repeated use.

[0033]In addition, of the above charge generation substances, an azo
compound represented by the following general formula (2) is also
preferable because a combination of the compound and the polyvinyl acetal
resin of the present invention provide excellent dispersion stability and
excellent coating property:

##STR00028##

where Ar21 and Ar22 each independently represent a substituted
or unsubstituted aryl group, X21 represents a vinylene group or a
p-phenylene group, and n represents 0 or 1. In addition, the combination
of the azo compound and the polyvinyl acetal resin of the present
invention exert improving effects on chargeability and sensitivity, and
an alleviating effect on a photomemory so that potential stability upon
repeated use is high.

[0034]When the photosensitive layer is a laminated photosensitive layer, a
mass ratio between the charge generation substance in the charge
generation layer and the polyvinyl acetal resin of the present invention
(charge generation substance: polyvinyl acetal resin) is preferably 5:1
to 1:2, or more preferably 3:1 to 1:1. When the amount of the polyvinyl
acetal resin is excessively small, an effect of the present invention
cannot be sufficiently obtained in some cases. When the amount of the
charge generation substance is excessively small, a charge generation
function cannot be sufficiently obtained in some cases.

[0035]In addition, the charge generation layer has a thickness of
preferably 5 μm or less, or more preferably 0.05 to 1 μm.

[0036]When the photosensitive layer is a laminated photosensitive layer, a
charge transport layer can be formed by: applying a coating liquid for a
charge transport layer prepared by dissolving a charge transport
substance and a binder resin in a solvent; and drying the applied liquid.

[0038]In addition, examples of the binding resin to be used for the charge
transport layer include a polyester resin, an acrylic resin, a
polyvinylcarbazole resin, a phenoxy resin, a polycarbonate resin, a
polyvinylbutyral resin, a polystyrene resin, a polyvinyl acetate resin, a
polysulfone resin, a polyarylate resin, and a vinylidene
chloride-acrylonitrile copolymer resin.

[0039]In addition, the charge transport layer has a thickness of
preferably 5 to 40 μm, or more preferably 10 to 30 μm.

[0040]When the photosensitive layer is a single-layer photosensitive
layer, the photosensitive layer can be formed by: applying a solution
containing such charge generation substance and charge transport
substance as described above, and the polyvinyl acetal resin of the
present invention; and drying the applied liquid.

[0041]The single-layer photosensitive layer has a thickness of preferably
5 to 40 μm, or more preferably 15 to 30 μm.

[0042]A support to be used in the electrophotographic photosensitive
member of the present invention has only to be one having conductivity
(conductive support), and examples of a material for the support include
aluminum, an aluminum alloy, copper, zinc, stainless steel, vanadium,
molybdenum, chromium, titanium, nickel, indium, gold, and platinum. A
support formed by coating the upper portion of a plastic (such as
polyethylene, polypropylene, polyvinyl chloride, polyethylene
terephthalate, or an acrylic resin) with such metal or alloy by a vacuum
deposition method is also permitted. A support obtained by coating the
upper portion of a substrate made of a plastic, a metal, or an alloy with
conductive particles (such as carbon black and silver particles) together
with a binder resin is also permitted. A support obtained by impregnating
a plastic or paper with conductive particles is also permitted. Examples
of the shape of the support include a drum shape, a sheet shape, and a
belt shape. The support is preferably of a shape optimum for an
electrophotographic apparatus to which the support is applied.

[0043]In the electrophotographic photosensitive member of the present
invention, a base layer (intermediate layer) having a function such as a
barrier function or an adhesion function may be provided for a gap
between the support and the photosensitive layer. The base layer can be
formed of, for example, casein, polyvinyl alcohol, nitrocellulose,
polyamide (such as nylon 6, nylon 66, nylon 610, copolymerized nylon, or
alkoxymethylated nylon), polyurethane, or aluminum oxide.

[0044]The base layer has a thickness of preferably 5 μm or less, or
more preferably 0.3 to 2 μm.

[0045]In addition, a protective layer may be provided on the
photosensitive layer for the purposes of protecting the photosensitive
layer and improving the durability of the electrophotographic
photosensitive member.

[0046]The protective layer can be formed by: applying, onto the
photosensitive layer, a coating liquid for a protective layer prepared by
dissolving a resin such as polyvinyl butyral, polyester, polycarbonate
(such as polycarbonate Z or denatured polycarbonate), polyamide,
polyimide, polyarylate, polyurethane, a styrene-butadiene copolymer, a
styrene-acrylic acid copolymer, or a styrene-acrylonitrile copolymer in a
solvent; and drying the applied liquid. Alternatively, the protective
layer can be formed by: applying the coating liquid for a protective
layer onto the photosensitive layer; and curing the liquid by heating the
liquid or by irradiating the liquid with, for example, an electron beam
or ultraviolet light.

[0047]The protective layer has a thickness of preferably 0.1 to 10 μm.

[0048]In addition, conductive particles, a UV absorber, lubricant
particles such as fluorine atom-containing resin particles, and the like
may be incorporated into the protective layer. Preferable examples of the
conductive particles include metal oxide particles made of tin oxide,
silica, or the like.

[0049]The electrophotographic photosensitive member of the present
invention can find use in a wide variety of applications including
electrophotographic copying machines, laser beam printers, CRT printers,
and electrophotographic plate making systems.

[0050]Next, an electrophotographic apparatus having the
electrophotographic photosensitive member of the present invention will
be described.

[0051]FIG. 1 shows an example of the schematic constitution of the
electrophotographic apparatus of the present invention.

[0052]In FIG. 1, reference numeral 1 represents a drum type
electrophotographic photosensitive member of the present invention which
rotates around an axis 1a in the direction indicated by an arrow at a
predetermined circumferential speed. The circumferential surface of the
electrophotographic photosensitive member 1 is charged by a charging
means 2 to have a positive or negative predetermined electric potential
in the course of the rotation. Next, at an exposure portion 3, the member
receives exposure light L (such as laser beam scanning exposure) from an
exposing means (not shown). As a result, electrostatic latent images
corresponding to exposure images are sequentially formed on the
circumferential surface of the electrophotographic photosensitive member.
The electrostatic latent images are then developed as toner images by a
developing means 4, and the toner images are sequentially transferred by
a transfer means 5 according to a corona mode (corona transfer means)
onto the surface of a transfer material 9 fed in synchronization with the
rotation of the electrophotographic photosensitive member 1 from a
sheet-feeding portion (not shown) to a space between the
electrophotographic photosensitive member 1 and the transfer means 5. The
transfer material 9 onto which the toner images have been transferred is
separated from the circumferential surface of the electrophotographic
photosensitive member and introduced into a fixing means 8 where the
images are fixed. As a result, the transfer material is printed out as a
copy to the outside of the electrophotographic apparatus. Transfer
residual toner on the circumferential surface of the electrophotographic
photosensitive member 1 after the transfer of the toner images is removed
by a cleaning means 6 so that the surface is cleaned. Then, the surface
is subjected to an antistatic treatment by a pre-exposing means 7 so that
the member is repeatedly used for image formation.

[0053]Alternatively, as shown in FIG. 2, a process cartridge may be
constituted, which: integrally supports an electrophotographic
photosensitive member and at least one means selected from the group
consisting of a charging means, a developing means, a transfer means, and
a cleaning means; and is detachably mountable in an electrophotographic
apparatus main body.

[0054]The process cartridge shown in FIG. 2 is obtained by storing the
electrophotographic photosensitive member 1, the charging means 2, and
the developing means 4 in a container 20. The process cartridge is
constituted so as to be detachably mountable in the electrophotographic
apparatus main body by a guiding means 12 such as a rail. The cleaning
means 6 may be, or may not be, placed in the container 20.

[0055]FIG. 3 shows another form of each of the process cartridge and
electrophotographic apparatus of the present invention. As shown in FIG.
3, each of the process cartridge and electrophotographic apparatus of the
present invention may charge the electrophotographic photosensitive
member 1 with the aid of a contact charging member 10 as a charging means
by bringing the contact charging member 10 to which a voltage has been
applied into contact with the electrophotographic photosensitive member 1
(the charging method is hereinafter referred to as "contact charging").
In the apparatus shown in FIG. 3, a toner image on the
electrophotographic photosensitive member 1 is also transferred onto the
transfer material 9 by a contact charging member 23 for transfer. That
is, the toner image on the electrophotographic photosensitive member 1 is
transferred onto the transfer material 9 by bringing the contact charging
member 23 for transfer to which a voltage has been applied into contact
with the transfer material 9.

[0056]Further, as shown in FIG. 4, the process cartridge and the
electrophotographic apparatus may be constituted as follows: the
electrophotographic photosensitive member 1 and the contact charging
member 10 are stored in a first container 21 to provide a first process
cartridge, and the developing means 4 is stored in a second container 22
to provide a second process cartridge.

[0057]When the electrophotographic apparatus is used as a copying machine
or a printer, light reflected from a manuscript or light that has
transmitted through the manuscript may be used as the exposure light L,
or a laser beam used in scanning in accordance with a signal obtained by
reading the manuscript and turning the read manuscript into the signal
may be used. Alternatively, the driving of a light-emitting diode array,
the driving of a liquid crystal shutter array, or the like may be
adopted.

[0058]Hereinafter, the present invention will be described in more detail
by way of examples. It should be noted that the term "part(s)" in the
following examples represents "part(s) by mass".

[0059]Infrared spectroscopy (IR) was performed by using an FT/IR-420
(manufactured by JASCO Corporation).

[0060]The X-ray diffraction of a crystal form was performed by using a
CuKα ray under the following conditions.

[0061]3 parts of polyvinyl alcohol (trade name: POVAL 1400, manufactured
by Kishida Chemical Co., Ltd.) and 54 parts of an aldehyde compound
represented by the following structural formula were stirred in 25 parts
of toluene and 25 parts of ethanol, and 0.2 part of concentrated
hydrochloric acid was dropped to the mixture.

##STR00029##

Then, the temperature of the resultant was increased to 50° C., and
the resultant was stirred for 5 hours under heat. The reactant was
dropped to 1,000 parts of methanol, in which 0.4 part of sodium hydroxide
had been dissolved, under stirring, and then the precipitate was
separated by filtration. The resultant remainder on the filter paper was
dissolved in 100 parts of toluene and 100 parts of acetone, and the
insoluble matter was removed by using fluted filter paper. After that,
the remainder was dropped to 2,000 parts of methanol under stirring, and
the precipitate was separated by filtration. The resultant remainder on
the filter paper was redissolved in 180 parts of a mixed solution of
toluene and acetone at a ratio of 1:1, and then the solution was dropped
to 2,000 parts of methanol under stirring. The precipitate was separated
by filtration, whereby 1.4 parts of Exemplified Resin (1) were obtained.
IR data on the resultant resin is shown below.

[0063]1.8 parts of polyvinyl alcohol (tradename: POVAL 1400, manufactured
by Kishida Chemical Co., Ltd.) and 34 parts of an aldehyde compound
represented by the following structural formula were stirred in 25 parts
of toluene and 25 parts of ethanol, and 0.2 part of concentrated
hydrochloric acid was dropped to the mixture.

##STR00030##

Then, the temperature of the resultant was increased to 50° C., and
the resultant was stirred for 5 hours under heat. The reactant was
dropped to 1,000 parts of methanol, in which 0.3 part of sodium hydroxide
had been dissolved, under stirring, and then the precipitate was
separated by filtration. The resultant remainder on the filter paper was
dissolved in 90 parts of toluene and 90 parts of acetone, and the
insoluble matter was removed by using fluted filter paper. After that,
the remainder was dropped to 2,000 parts of methanol under stirring, and
the precipitate was separated by filtration. The resultant remainder on
the filter paper was redissolved in 50 parts of toluene and 30 parts of
acetone, and then the solution was dropped to 2,000 parts of methanol
under stirring. The precipitate was separated by filtration, whereby 1.6
parts of Exemplified Resin (3) were obtained. IR data on the resultant
resin is shown below.

[0065]1.7 parts of polyvinyl alcohol (trade name: POVAL 1400, manufactured
by Kishida Chemical Co., Ltd.) and 33 parts of an aldehyde compound
represented by the following structural formula were stirred in 25 parts
of toluene and 25 parts of ethanol, and 0.2 part of concentrated
hydrochloric acid was dropped to the mixture.

##STR00031##

Then, the temperature of the resultant was increased to 50° C., and
the resultant was stirred for 8 hours under heat. The reactant was
dropped to 1,000 parts of methanol, in which 0.3 part of sodium hydroxide
had been dissolved, under stirring, and then the precipitate was
separated by filtration. The resultant remainder on the filter paper was
dissolved in 100 parts of toluene and 100 parts of acetone, and the
insoluble matter was removed by using fluted filter paper. After that,
the remainder was dropped to 2,000 parts of methanol under stirring, and
the precipitate was separated by filtration. The resultant remainder on
the filter paper was redissolved in 80 parts of toluene and 80 parts of
acetone, and then the solution was dropped to 2,000 parts of methanol
under stirring. The precipitate was separated by filtration, whereby 4.4
parts of Exemplified Resin (7) were obtained. IR data on the resultant
resin is shown below.

[0067]3.4 parts of polyvinyl alcohol (trade name: POVAL 1400, manufactured
by Kishida Chemical Co., Ltd.) and 70 parts of an aldehyde compound
represented by the following structural formula were stirred in 80 parts
of toluene and 80 parts of ethanol, and 0.2 part of concentrated
hydrochloric acid was dropped to the mixture.

##STR00032##

Then, the temperature of the resultant was increased to 50° C., and
the resultant was stirred for 6 hours under heat. The reactant was
dropped to 1,500 parts of methanol, in which 0.3 part of sodium hydroxide
had been dissolved, under stirring, and then the precipitate was
separated by filtration. The resultant remainder on the filter paper was
dissolved in 150 parts of toluene and 150 parts of acetone, and the
insoluble matter was removed by using sellite filtration. After that, the
remainder was dropped to 2,000 parts of methanol under stirring, and the
precipitate was separated by filtration. The resultant remainder on the
filter paper was redissolved in 100 parts of toluene and 100 parts of
acetone, and then the solution was dropped to 2,000 parts of methanol
under stirring. The precipitate was separated by filtration, whereby 2.5
parts of Exemplified Resin (10) were obtained. IR data on the resultant
resin is shown below.

[0069]2.7 parts of polyvinyl alcohol (tradename: POVAL 1400, manufactured
by Kishida Chemical Co., Ltd.) and 46 parts of an aldehyde compound
represented by the following structural formula were stirred in 35 parts
of toluene and 35 parts of ethanol, and 0.4 part of concentrated
hydrochloric acid was dropped to the mixture.

##STR00033##

Then, the temperature of the resultant was increased to 50° C., and
the resultant was stirred for 6 hours under heat. The reactant was
dropped to 1,000 parts of methanol, in which 0.4 part of sodium hydroxide
had been dissolved, under stirring, and then the precipitate was
separated by filtration. The resultant remainder on the filter paper was
dissolved in 50 parts of toluene and 50 parts of acetone, and the
insoluble matter was removed by using fluted filter paper. After that,
the remainder was dropped to 2,000 parts of methanol under stirring, and
the precipitate was separated by filtration. The resultant remainder on
the filter paper was redissolved in 50 parts of toluene and 50 parts of
acetone, and then the solution was dropped to 2,000 parts of methanol
under stirring. The precipitate was separated by filtration, whereby 1.0
part of Comparative Resin (A) as a polyvinyl acetal resin having a
repeating structural unit represented by the following structural formula
was obtained.

[0072]4.4 parts of polyvinyl alcohol (tradename: POVAL 1400, manufactured
by Kishida Chemical Co., Ltd.) and 75 parts of an aldehyde compound
represented by the following structural formula were stirred in 100 parts
of toluene and 100 parts of ethanol, and 0.3 part of concentrated
hydrochloric acid was dropped to the mixture.

##STR00035##

Then, the temperature of the resultant was increased to 50° C., and
the resultant was stirred for 7 hours under heat. The reactant was
dropped to 1,000 parts of methanol, in which 0.3 part of sodium hydroxide
had been dissolved, under stirring, and then the precipitate was
separated by filtration. The resultant remainder on the filter paper was
dissolved in 150 parts of toluene and 150 parts of acetone, and the
insoluble matter was removed by using sellite filtration. After that, the
remainder was dropped to 2,000 parts of methanol under stirring, and the
precipitate was separated by filtration. The resultant remainder on the
filter paper was redissolved in 200 parts of toluene and 100 parts of
acetone, and then the solution was dropped to 2,000 parts of methanol
under stirring. The precipitate was separated by filtration, whereby 9.1
part of Comparative Resin (B) as a polyvinyl acetal resin having a
repeating structural unit represented by the following structural formula
was obtained.

[0075]An aluminum cylinder having a diameter of 30 mm and a length of
357.5 mm was used as a support.

[0076]The upper portion of the support was immersed in and coated with a
coating liquid constituted of the following materials, and the resultant
was dried for 30 minutes at 140° C., whereby a conductive layer
(interference fringe preventing layer) having a thickness of 18 μm was
formed.

[0077]Next, 1 part of N-methoxymethylated nylon and 3 parts of
copolymerized nylon were dissolved in a mixed solvent of 60 parts of
methanol and 30 parts of n-butanol, whereby a coating liquid for a base
layer (intermediate layer) was prepared.

[0078]The upper portion of the conductive layer was immersed in and coated
with the coating liquid for a base layer (intermediate layer), and the
resultant was dried for 10 minutes at 100° C., whereby a base
layer (intermediate layer) having a thickness of 0.6 μm was formed.

[0079]Next, 10 parts of a hydroxygallium phthalocyanine crystal (charge
generation substance) having a strong peak at a Bragg angle
2θ±0.2° in CuKα characteristic X-ray diffraction of
each of 7.5° and 28.3°, 5 parts of Exemplified Resin (1)
obtained in the Synthesis Example 1, and 200 parts of cyclohexanone were
dispersed for 6 hours with a sand mill device using glass beads each
having a diameter of 0.8 mm. After that, 170 parts of cyclohexanone and
380 parts of ethyl acetate were added to the mixture, whereby a coating
liquid for a charge generation layer was prepared.

[0080]The upper portion of the base layer (intermediate layer) was
immersed in and coated with the coating liquid for a charge generation
layer, and the resultant was dried for 10 minutes at 80° C.,
whereby a charge generation layer having a thickness of 0.18 μm was
formed.

[0081]Next, 10 parts of a compound represented by the following structural
formula (CTM-1) (charge transport substance) and 10 parts of a
polycarbonate resin (trade name: Lupilon Z-200, manufactured by
Mitsubishi Engineering-Plastics Corporation) were dissolved in a mixed
solvent of 90 parts of monochlorobenzene and 20 parts of dichloromethane,
whereby a coating liquid for a charge transport layer was prepared.

##STR00037##

[0082]The upper portion of the charge generation layer was immersed in and
coated with the coating liquid for a charge transport layer, and the
resultant was dried for 60 minutes at 110° C., whereby a charge
transport layer having a thickness of 20 μm was formed.

[0083]Thus, the electrophotographic photosensitive member 1 was produced.

[0084](Evaluation for Photosensitive Property)

[0085]The photosensitive property of the electrophotographic
photosensitive member 1 was measured by using an electrophotographic
photosensitive member measuring device according to a direct voltage
application mode using bent NESA glass. A measurement sequence was a
sequence for a capacitor model in which the electrophotographic
photosensitive member was regarded as a capacitor.

[0086]The measurement is advanced as shown in FIG. 5.

[0087]To be specific, first, in order that the hysteresis of the
electrophotographic photosensitive member might be eliminated, the
electrophotographic photosensitive member was irradiated with exposure
light (image exposure light) and pre-exposure light, and, 10 milliseconds
after the irradiation, a predetermined applied voltage (Va) was applied
to the electrophotographic photosensitive member. Next, 20 milliseconds
after the application, the electric potential (Vd+Vc) of the member was
measured. After the measurement, the electric potential of the
electrophotographic photosensitive member was grounded. Next, an electric
potential (Vc) allotted to a capacitor inserted into a measuring
instrument was measured. A surface potential (Vd) determined from those
results was defined as the electric potential of the electrophotographic
photosensitive member.

[0088]It should be noted that, 20 milliseconds after the surface potential
(Vd) had reached -700 V, light obtained by dispersing halogen light with
an interference filter capable of extracting light having a wavelength
(image exposure wavelength) of 403 nm was applied for 100 milliseconds,
and, 395 milliseconds after the application, the surface potential was
measured. Photosensitivity (Δ500) was determined from a light
quantity (cJ/m2) at which the surface potential (Vd) reached -200V
owing to exposure (image exposure). In addition a surface potential 500
milliseconds after the application of halogen light (pre-exposure light)
with 1,600 Lux for 100 milliseconds was defined as a residual potential.

[0089](Evaluation for Photomemory Property)

[0090]The dark potential (VD) of the electrophotographic photosensitive
member was set to -700 V, and the light potential (VL) of the member with
light obtained as a result of dispersion with an interference filter
capable of extracting light having a wavelength of 403 nm was set to -200
V. Next, part of the electrophotographic photosensitive member was
irradiated with light from a fluorescent lamp with 1,500 Lux for 5
minutes, and then the member was left in a dark place for 3 minutes.
After that, the dark potential (VD) and light potential (VL) of the
electrophotographic photosensitive member were measured again, and a
difference in VD (ΔVDPM) between a non-irradiated portion and an
irradiated portion and a difference in VL (ΔVLPM) between the
non-irradiated portion and the irradiated portion were each measured as a
photomemory.

[0091](Evaluation for Coating Property)

[0092]A coating liquid for a charge generation layer prepared in each of
examples and comparative examples was evaluated for coating property by
visually evaluating the external appearance of a surface coated with the
liquid.

[0093](Evaluation for Dispersion Stability)

[0094]The particle size of a charge generation substance in an initial
coating liquid for a charge generation layer prepared in each of examples
and comparative examples was measured with a centrifugal sedimentation
type grain size distribution measuring device CAPA-700 (manufactured by
HORIBA, Ltd.). After that, the coating liquid was stationary stored for 3
months. Then, the coating liquid was visually evaluated for dispersed
state, and the particle size of the charge generation substance was
similarly measured and evaluated.

[0095]Table 1 shows the above results.

[0096](Actual Machine Evaluation)

[0097]The electrophotographic photosensitive member 1 was evaluated for
durable electric potential property by using a reconstructed device of a
copying machine GP-40 manufactured by Canon Inc. (obtained by: changing a
light source to semiconductor laser (blue laser) having a wavelength of
405 nm; and changing pre-exposure to a halogen lamp). An electric
potential was measured by: removing a developing unit from the main body
of the copying machine; and fixing a probe for measuring an electric
potential at a developing position instead of the developing unit. At
that time, a transfer unit was out of contact with the
electrophotographic photosensitive member, and no paper was passed.

[0098]Charging setting was performed and an image exposure value was
adjusted in such a manner that the dark potential (VD) would be -700 V
and the light potential (VL) would be -200 V under a normal-temperature,
normal-humidity environment (N/N) having a temperature of 23° C.
and a humidity of 50% RH. In addition, a pre-exposure value was adjusted
so as to be twice as large as the halogen light quantity at which a
surface potential of -700 V was attenuated to -200 V. After that, VL
duration involving 2,000 consecutive rotations (meaning a durability test
in a full-screen black image mode) was performed, and a light potential
at the 2,000-th rotation was measured. A difference between an initial VL
and a VL at the 2,000-th rotation was defined as a "variation after 2,000
times of duration".

[0099]In addition, the electrophotographic photosensitive member 1 was
left together with an evaluation machine under a normal-temperature,
low-humidity environment (N/L) having a temperature of 23° C. and
a humidity of 5% RH for 3 days. After that, charging setting was
performed and an image exposure value was adjusted in such a manner that
the dark potential (VD) would be -700 V and the light potential (VL)
would be -200 V under the same environment (N/L). In addition, a
pre-exposure value was adjusted so as to be twice as large as the halogen
light quantity at which a surface potential of -700 V was attenuated to
-200 V. After that, VL duration involving 2,000 consecutive rotations was
performed, and a light potential at the 2,000-th rotation was measured. A
difference between an initial VL and a VL at the 2,000-th rotation was
defined as a "variation after 2,000 times of duration".

[0100]In addition, the electrophotographic photosensitive member 1 was
left together with an evaluation machine under a high-temperature,
high-humidity environment (H/H) having a temperature of 30° C. and
a humidity of 80% RH for 3 days. After that, charging setting was
performed and an image exposure value was adjusted in such a manner that
the dark potential (VD) would be -700 V and the light potential (VL)
would be -200 V under the same environment (H/H). In addition, a
pre-exposure value was adjusted so as to be twice as large as the halogen
light quantity at which a surface potential of -700 V was attenuated to
-200 V. After that, VL duration involving 2,000 consecutive rotations was
performed, and a light potential at the 2,000-th rotation was measured. A
difference between an initial VL and a VL at the 2,000-th rotation was
defined as a "variation after 2,000 times of duration".

[0101]Table 2 shows the above results.

EXAMPLE 2

[0102]An electrophotographic photosensitive member 2 was produced in the
same manner as in Example 1 except that Exemplified Resin (1) used in the
charge generation layer in Example 1 was changed to Exemplified Resin (3)
obtained in the Synthesis Example 2, and the member was evaluated in the
same manner as in Example 1.

[0103]Tables 1 and 2 show the results.

EXAMPLE 3

[0104]An electrophotographic photosensitive member 3 was produced in the
same manner as in Example 1 except that Exemplified Resin (1) used in the
charge generation layer in Example 1 was changed to Exemplified Resin (7)
obtained in the Synthesis Example 3, and the member was evaluated in the
same manner as in Example 1.

[0105]Tables 1 and 2 show the results.

EXAMPLE 4

[0106]An electrophotographic photosensitive member 4 was produced in the
same manner as in Example 1 except that Exemplified Resin (1) used in the
charge generation layer in Example 1 was changed to Exemplified Resin
(10) obtained in the Synthesis Example 4, and the member was evaluated in
the same manner as in Example 1.

[0107]Tables 1 and 2 show the results.

EXAMPLE 11

[0108]An electrophotographic photosensitive member 11 was produced in the
same manner as in Example 1 except that the hydroxygallium phthalocyanine
crystal having a strong peak at a Bragg angle 2θ±0.2° in
CuKα characteristic X-ray diffraction of each of 7.5° and
28.3° used in the charge generation layer in Example 1 was changed
to an oxytitanium phthalocyanine crystal having a strong peak at a Bragg
angle 2θ±0.2° in CuKα characteristic X-ray
diffraction of each of 9.0° and 27.1°, and the member was
evaluated in the same manner as in Example 1.

[0109]Tables 1 and 2 show the results.

EXAMPLE 21

[0110]A conductive layer (interference fringe preventing layer) and a base
layer (intermediate layer) were formed on a support (aluminum cylinder)
in the same manner as in Example 1.

[0111]Next, 10 parts of an azo compound (charge generation substance)
represented by the following structural formula (CGM-1) and 200 parts of
cyclohexanone were dispersed for 20 hours with a sand mill device using
300 parts of glass beads each having a diameter of 0.8 mm.

##STR00038##

After that, a solution prepared by dissolving 5 parts of Exemplified Resin
(1) obtained in the Synthesis Example 1 in 50 parts of cyclohexanone was
added to the mixture. Then, the resultant was dispersed with the sand
mill device for an additional 3 hours. After that, 150 parts of
cyclohexanone and 350 parts of 2-butanone were added to the resultant,
whereby a coating liquid for a charge generation layer was prepared.

[0112]The upper portion of the base layer (intermediate layer) was
immersed in and coated with the coating liquid for a charge generation
layer, and the resultant was dried for 10 minutes at 80° C.,
whereby a charge generation layer having a thickness of 0.20 μm was
formed.

[0113]Next, a charge transport layer was formed on the charge generation
layer in the same manner as in Example 1.

[0114]Thus, an electrophotographic photosensitive member 21 was produced.

[0115]The resultant electrophotographic photosensitive member 21 was
evaluated in the same manner as in Example 1.

[0116]Tables 1 and 2 show the results.

EXAMPLE 22

[0117]An electrophotographic photosensitive member 22 was produced in the
same manner as in Example 21 except that Exemplified Resin (1) used in
the charge generation layer in Example 21 was changed to Exemplified
Resin (3) obtained in the Synthesis Example 2, and the member was
evaluated in the same manner as in Example 1.

[0118]Tables 1 and 2 show the results.

EXAMPLE 23

[0119]An electrophotographic photosensitive member 23 was produced in the
same manner as in Example 21 except that Exemplified Resin (1) used in
the charge generation layer in Example 21 was changed to Exemplified
Resin (7) obtained in the Synthesis Example 3, and the member was
evaluated in the same manner as in Example 1.

[0120]Tables 1 and 2 show the results.

EXAMPLE 24

[0121]An electrophotographic photosensitive member 24 was produced in the
same manner as in Example 21 except that Exemplified Resin (1) used in
the charge generation layer in Example 21 was changed to Exemplified
Resin (10) obtained in the Synthesis Example 4, and the member was
evaluated in the same manner as in Example 1.

[0122]Tables 1 and 2 show the results.

EXAMPLE 31

[0123]An electrophotographic photosensitive member 31 was produced in the
same manner as in Example 21 except that the azo compound represented by
the above structural formula (CGM-1) used in the charge generation layer
in Example 21 was changed to a mixture of 4 kinds of azo compounds, that
is, an azo compound represented by the following structural formula
(CGM-2), an azo compound represented by the following structural formula
(CGM-3), an azo compound represented by the following structural formula
(CGM-4), and an azo compound represented by the following structural
formula (CGM-5), and the member was evaluated in the same manner as in
Example 1.

##STR00039##

EXAMPLE 32

[0124]An electrophotographic photosensitive member 32 was produced in the
same manner as in Example 31 except that Exemplified Resin (1) used in
the charge generation layer in Example 31 was changed to Exemplified
Resin (3) obtained in the Synthesis Example 2, and the member was
evaluated in the same manner as in Example 1.

[0125]Tables 1 and 2 show the results.

EXAMPLE 33

[0126]An electrophotographic photosensitive member 33 was produced in the
same manner as in Example 31 except that Exemplified Resin (1) used in
the charge generation layer in Example 31 was changed to Exemplified
Resin (7) obtained in the Synthesis Example 3, and the member was
evaluated in the same manner as in Example 1.

[0127]Tables 1 and 2 show the results.

EXAMPLE 34

[0128]An electrophotographic photosensitive member 34 was produced in the
same manner as in Example 31 except that Exemplified Resin (1) used in
the charge generation layer in Example 31 was changed to Exemplified
Resin (10) obtained in the Synthesis Example 4, and the member was
evaluated in the same manner as in Example 1.

[0129]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 1

[0130]A comparative electrophotographic photosensitive member 1 was
produced in the same manner as in Example 1 except that Exemplified Resin
(1) used in the charge generation layer in Example 1 was changed to a
polyvinyl butyral resin (trade name: S-REC BX-1, manufactured by SEKISUI
CHEMICAL CO., LTD.), and the member was evaluated in the same manner as
in Example 1.

[0131]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 2

[0132]An comparative electrophotographic photosensitive member 2 was
produced in the same manner as in Example 1 except that Exemplified Resin
(1) used in the charge generation layer in Example 1 was changed to
Comparative Resin (A) obtained in the Comparative Synthesis Example 1,
and the member was evaluated in the same manner as in Example 1.

[0133]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 3

[0134]An comparative electrophotographic photosensitive member 3 was
produced in the same manner as in Example 1 except that Exemplified Resin
(1) used in the charge generation layer in Example 1 was changed to
Comparative Resin (B) obtained in the Comparative Synthesis Example 2,
and the member was evaluated in the same manner as in Example 1.

[0135]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 4

[0136]A comparative electrophotographic photosensitive member 4 was
produced in the same manner as in Example 1 except that Exemplified Resin
(1) used in the charge generation layer in Example 1 was changed to
Comparative Resin (C) having a repeating structural unit represented by
the following structural formula, and the member was evaluated in the
same manner as in Example 1.

##STR00040##

[0137]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 5

[0138]A comparative electrophotographic photosensitive member 5 was
produced in the same manner as in Example 1 except that Exemplified Resin
(1) used in the charge generation layer in Example 1 was changed to
Comparative Resin (D) having a repeating structural unit represented by
the following structural formula, and the member was evaluated in the
same manner as in Example 1.

##STR00041##

[0139]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 11

[0140]A comparative electrophotographic photosensitive member 11 was
produced in the same manner as in Example 11 except that Exemplified
Resin (1) used in the charge generation layer in Example 11 was changed
to a polyvinyl butyral resin (trade name: S-REC BX-1, manufactured by
SEKISUI CHEMICAL CO., LTD.), and the member was evaluated in the same
manner as in Example 1.

[0141]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 21

[0142]A comparative electrophotographic photosensitive member 21 was
produced in the same manner as in Example 21 except that Exemplified
Resin (1) used in the charge generation layer in Example 21 was changed
to a polyvinyl butyral resin (trade name: S-REC BX-1, manufactured by
SEKISUI CHEMICAL CO., LTD.), and the member was evaluated in the same
manner as in Example 1.

[0143]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 22

[0144]A comparative electrophotographic photosensitive member 22 was
produced in the same manner as in Example 21 except that Exemplified
Resin (1) used in the charge generation layer in Example 21 was changed
to Comparative Resin (A) obtained in the Comparative Synthesis Example 1,
and the member was evaluated in the same manner as in Example 1.

[0145]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 23

[0146]A comparative electrophotographic photosensitive member 23 was
produced in the same manner as in Example 21 except that Exemplified
Resin (1) used in the charge generation layer in Example 21 was changed
to Comparative Resin (B) obtained in the Comparative Synthesis Example 2,
and the member was evaluated in the same manner as in Example 1.

[0147]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 24

[0148]A comparative electrophotographic photosensitive member 24 was
produced in the same manner as in Example 21 except that Exemplified
Resin (1) used in the charge generation layer in Example 21 was changed
to aforementioned Comparative Resin (C), and the member was evaluated in
the same manner as in Example 1.

[0149]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 25

[0150]A comparative electrophotographic photosensitive member 25 was
produced in the same manner as in Example 21 except that Exemplified
Resin (1) used in the charge generation layer in Example 21 was changed
to aforementioned Comparative Resin (D), and the member was evaluated in
the same manner as in Example 1.

[0151]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 31

[0152]A comparative electrophotographic photosensitive member 31 was
produced in the same manner as in Example 31 except that Exemplified
Resin (1) used in the charge generation layer in Example 31 was changed
to a polyvinyl butyral resin (trade name: S-REC BX-1, manufactured by
SEKISUI CHEMICAL CO., LTD.), and the member was evaluated in the same
manner as in Example 1.

[0153]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 32

[0154]A comparative electrophotographic photosensitive member 32 was
produced in the same manner as in Example 31 except that Exemplified
Resin (1) used in the charge generation layer in Example 31 was changed
to Comparative Resin (B) obtained in the Comparative Synthesis Example 2,
and the member was evaluated in the same manner as in Example 1.

[0155]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 33

[0156]A comparative electrophotographic photosensitive member 33 was
produced in the same manner as in Example 31 except that Exemplified
Resin (1) used in the charge generation layer in Example 31 was changed
to aforementioned Comparative Resin (C), and the member was evaluated in
the same manner as in Example 1.

[0157]Tables 1 and 2 show the results.

COMPARATIVE EXAMPLE 34

[0158]A comparative electrophotographic photosensitive member 34 was
produced in the same manner as in Example 31 except that Exemplified
Resin (1) used in the charge generation layer in Example 31 was changed
to aforementioned Comparative Resin (D), and the member was evaluated in
the same manner as in Example 1.

[0160]A "variation after 2,000 times of duration" having a + sign in Table
2 means that a light potential increased while a "variation after 2,000
times of duration" having a - sign means that a light potential reduced.
In the case of, for example, N/L of Comparative Example 34, a light
potential after VL duration involving 2,000 consecutive rotations is
-200-(-35)=-165 [V].

[0161]While the present invention has been described with reference to
exemplary embodiments, it is to be understood that the invention is not
limited to the disclosed exemplary embodiments. The scope of the
following claims is to be accorded the broadest interpretation so as to
encompass all such modifications and equivalent structures and functions.

[0162]This application claims the benefit of Japanese Patent Application
No. 2005-353490, filed on Dec. 7, 2005, which is hereby incorporated by
reference herein in its entirety.